It is a great challenge to train a pet animal, such as a dog, to behave on a leash. The animal's natural instinct is to pull on the leash which forces the owner to expend energy to control the animal. Large animals often exert such forces on their leashes as to tax the owner or possibly exceed the ability of the owner to hold on to the dog.
One common method for training and controlling animals on a leash is the choke collar or choke chain. Choke collars restrain animals by choking off breathing to a degree proportional to the strain imposed by the animal on the collar. The choking pressure is eased as the animal relaxes its pull upon the leash.
Choke collars, however, are not the ideal solution to this problem. Many animals will stubbornly fight the choke collar despite the painful pressure it exerts on the animal's throat. As a result, choke collars will often break off and pull out hairs or otherwise damage the skin and/or coat of the animal. Therefore, choke collars are considered by many to be an inhumane method of training an animal to behave on a leash.